How Many Liters Is a Carry-On?
The standard box works out at about 45 liters of geometry. Real bags publish 35 to 46, and the gap between those two numbers is the whole answer.
We have not tested this gear. Every figure here is compiled from published manufacturer specifications and published airline policies, and the arithmetic is public so you can check it. This page contains affiliate links — see the affiliate disclosure.
The standard 22 × 14 × 9 in carry-on box is 2,772 in³, which is 45.4 liters. Real bags built to that box publish 35 to 46 L of usable capacity, because tapered corners, wheel housings, handle trolleys and shell thickness all consume volume that the outside dimensions include.
Conversion: 1 in³ = 0.0163871 L. Every capacity figure quoted below is the manufacturer’s published number, compiled 3 September 2026 — not a calculation of ours.
The conversion, worked
There is nothing clever here, but it is worth seeing once because it makes every later number readable. One cubic inch is 0.0163871 liters. So for the standard box:
- 22 × 14 × 9 = 2,772 in³
- 2,772 × 0.0163871 = 45.4 L
That is the volume of the box, not of any bag that fits it. It is the theoretical ceiling — a perfect rectangular prism with infinitely thin walls, no wheels and no handle.
Why real bags publish less
Four things eat the difference between the box and the bag, and they are worth naming because they explain why two bags with identical outside dimensions can publish capacities 10 L apart.
- Shell thickness. A polycarbonate shell is a few millimeters on each of six faces. That is a couple of liters before anything else.
- Wheel housings. On a spinner, four wheel wells intrude into the bottom of the packing space. This is the single biggest loss and it is why a wheeled bag always loses to a backpack of the same outside dimensions.
- The handle trolley. Two aluminum tubes run the full height of most cases. Some makers route them outside the liner, most route them through it, and the ridge they create is dead space.
- Taper and radius. Almost no case is a true rectangular prism — the corners are radiused and the sides taper, both for strength and for molding.
What real bags publish
| Bag | Published overall size | Box volume | Published capacity | Loss |
|---|---|---|---|---|
| Travelpro Maxlite 5 Carry-On Spinner | 23 × 14.5 × 9 in | 49.2 L | 46 L | 7% |
| Travelpro Platinum Elite Carry-On Spinner | 23.5 × 14.5 × 9 in | 50.3 L | 46 L | 9% |
| Amazon Basics Hardside Spinner | 21.6 × 14.9 × 10 in | 52.7 L | 39 L | 26% |
| LEVEL8 Road Runner Carry-On | 21.5 × 14.4 × 9.2 in | 46.7 L | 35 L | 25% |
| Osprey Farpoint 40 Travel Pack | 21.7 × 13.8 × 9.1 in | 44.6 L | 40 L | 10% |
| Osprey Daylite Duffel 45 | 21 × 14 × 9 in | 43.4 L | 45 L | −4% |
Two things jump out of that table. First, the loss varies from 7% to 26% across bags of near-identical outside size — so “22-inch carry-on” tells you almost nothing about how much it holds. Second, the duffel has a negative loss: it publishes 45 L inside a box that computes to 43.4 L. That is not an error, it is what soft bags do. They expand past their nominal dimensions when packed, which is a capacity advantage and a measuring problem at the same time.
The other published boxes in liters
| Published carry-on limit | Carriers | Volume in liters |
|---|---|---|
| 22 × 14 × 9 in | American, Delta, United, Alaska, JetBlue, Hawaiian, Breeze | 45.4 L |
| 22 × 16 × 10 in | Allegiant | 57.7 L |
| 24 × 16 × 10 in | Southwest, Frontier | 62.9 L |
| 24 × 16 × 11 in | Sun Country | 69.2 L |
| 18 × 14 × 8 in | American, Frontier, Allegiant (personal item) | 33 L |
| 17 × 10 × 9 in | United (personal item) | 25.1 L |
So what capacity should you actually buy?
For a carry-on-only trip of up to a week, 35 to 40 L is the working range for most people, and there is a good structural reason for it rather than just a convention. A bag whose published capacity approaches the 45 L box volume is almost certainly achieving it by being bigger on the outside than the box allows — which is exactly the trap in the first table on this page, where two bags publish 46 L and both are over the standard height limit.
- 30–35 L — three or four days, or a week if you do laundry. Comfortably inside every published box.
- 35–40 L — a week, packed deliberately. This is where most one-bag packs sit.
- 40–45 L — a week with bulk (a coat, boots, camera gear). Check the outside dimensions carefully; this is where bags start failing sizers.
- Over 45 L — not a carry-on on any US carrier that publishes 22 × 14 × 9 in, whatever the listing says.
Bags with published capacities that fit the published box
Each of these publishes both a capacity figure and dimensions that clear the standard 22 × 14 × 9 in box — which is a smaller overlap than you would expect.
Osprey Fairview 40 Travel Pack
22 × 14 × 9 in · fits 11 of 11 US carriers
Shorter torsos, and anyone the Farpoint's shoulder straps do not suit
Tortuga Travel Backpack Pro 40L
22 × 14 × 8 in · fits 11 of 11 US carriers
Readers who want the tightest published depth in a 40 L bag
Not sold on Amazon#ad How we earnEagle Creek Cargo Hauler Duffel 40L
22 × 12.5 × 9 in · fits 11 of 11 US carriers
A duffel that will actually pass a gate sizer
Osprey Daylite Duffel 45
21 × 14 × 9 in · fits 11 of 11 US carriers
Maximum published volume that still clears a 22 × 14 × 9 in sizer
Full rankings: carry-on luggage · carry-on backpacks · carry-on duffels